Cervical spine stabilization system with extendable plates

ABSTRACT

A spine stabilization system having a base plate having a plurality of screw holes and a plurality of corresponding screw locking mechanisms. The present invention also provides an extension plate having a plurality of screw holes and corresponding screw locking mechanisms. The extension plate is dimensioned and configured with an extension portion, the extension portion having a screw hole and a screw locking mechanism and a finger portion having a connection element and to contact and connect with the base plate. The base plate is provided a graft window having edges, wherein at least one of the edges being configured to receive and connect with the connection element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 12/275,348, filed Nov. 21, 2008, which claims thebenefit of U.S. Provisional Application No. 60/989,622, filed on Nov.21, 2007.

FIELD OF THE INVENTION

The present invention is generally directed for use in a cervical spinestabilization system. In particular, the present invention is directedto a cervical spine stabilization system for the anterior cervicalregion of the human spine that specifically addresses an adjacent levelcondition and provides additional segments for the cervical spinestabilization system.

BACKGROUND OF THE INVENTION

In the United States, millions are affected by neck pain. Most patientsrespond well to non-surgical treatments. However, many others arerequired to find other solutions to alleviate the pain. If the neck painpersists and in addition, other symptoms such as arm pain andneurological dysfunction occur, the cause may be a cervicalintervertebral disc that has herniated. A disc herniates when some ofthe disc's gel like center bulges or ruptures through the outer ring ofthe disc and presses on nerve roots or the spinal cord. Surgery is anoption for those suffering from this type of nerve compression. Toalleviate the pain, a surgeon may perform a procedure called an anteriorcervical discectomy and fusion. In this procedure the surgeon makes asmall incision in the front of the neck to reach the cervical spine. Thedisc is removed and the space is filled with a bone graft. A cervicalplate is then screwed into the superior and inferior vertebral bones,which stabilizes the cervical spine facilitating fusion and healing.

However, a second surgery may be required to repair bone injuries toadjacent bone segments. Adjacent segment disease is a documented problemwithin the human cervical spine. As a result, surgeons currently removethe plate that was used to the fuse the original segment and position anew plate in its position. Other solutions to overcome this problem havebeen used. In one instance, the original plate is lifted up at one endand a larger second plate is positioned underneath the original plateand tightened down, thereby compressing and stabilizing the originalplate and the new larger plate. However, the procedural requirementalong with the size and connection method for this solution have createdadditional problems. Thus, the present art does not provide a novelsystem for additional plates to be attached to the base plate with ease,i.e. minimal incision during surgery. Therefore, there is a need for acervical plating system having the ability to incorporate additionalplates that can be attached to the base plate with minimal surgery timeand alleviate the problems associated with adjacent segment disease.

SUMMARY OF THE INVENTION

The present invention provides an anterior spine stabilization systemhaving a base plate that has a plurality of screw holes and a pluralityof corresponding screw locking mechanisms and an extension plate havinga plurality of screw holes and corresponding screw locking mechanisms.The extension plate is dimensioned and configured with an extensionportion, and the extension portion is provided with an angled screw holeand a screw locking mechanism. The extension portion is also providedwith a finger portion having a connection element to contact and connectwith the base plate. The base plate is provided with graft windowshaving edges and at least one of the edges being configured to receiveand connect with the connection element.

BRIEF DESCRIPTION OF THE DRAWINGS

The attached figures illustrate the different embodiments of the presentinvention.

FIG. 1 is an isometric view of one particular embodiment of the presentinvention;

FIG. 2 is a top view of the present invention illustrated in FIG. 1;

FIG. 3 is a top view of the present invention according the embodimentillustrated in FIG. 1;

FIG. 4 is a bottom view of the present invention according to theembodiment illustrated in FIG. 1;

FIG. 5 is an isometric view of the base plate according to the presentinvention;

FIG. 6 is a bottom view of the base plate shown in FIG. 5;

FIG. 7 is an isometric view of an extension plate according the presentinvention;

FIG. 8A is a bottom view of the extension plate according to the presentinvention;

FIG. 8B is a cross-sectional view of the connection between the baseplate and the extension plate;

FIGS. 9A-9C illustrate a plate holding instrument in various viewsaccording the present invention;

FIG. 10 illustrates the plate system according to present invention;

FIG. 11 is an isometric view of another embodiment of the presentinvention;

FIG. 12 is a bottom view of the embodiment illustrated in FIG. 11;

FIGS. 13A-13E are the top, bottom and side views of the base plateaccording to another embodiment of the present invention;

FIGS. 14A-14E are the top, bottom and side views of the adjacent segmentplate according another embodiment of the present invention;

FIGS. 15A-15E are the top, bottom and side views of the fasteningelement according one embodiment of the present invention;

FIG. 16 is an isometric view of the base plate and the adjacent segmentplate according the another embodiment of the present invention;

FIGS. 17A-17C are the top, bottom and side view of the plating systemaccording to the embodiment illustrated in FIG. 16;

FIGS. 18A-18E are the additional embodiments of the base plate and theadjacent segment plate according to the present invention;

FIGS. 19 and 20 illustrate additional embodiments of the extension plateaccording to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention will now be described. The followingdetailed description of the invention is not intended to be illustrativeof all embodiments. In describing embodiments of the present invention,specific terminology is employed for the sake of clarity. However, theinvention is not intended to be limited to the specific terminology soselected. It is to be understood that each specific element includes alltechnical equivalents that operate in a similar manner to accomplish asimilar purpose.

While the invention herein disclosed has been described by means ofspecific embodiments and applications thereof, numerous modificationsand variations can be made thereto by those skilled in the art withoutdeparting from the scope of the invention.

The present invention includes a base plate provided with featuresformed within the geometry of the plate to allow for joining of theextension plates. These additional plates can be later added in both thesuperior and the inferior directions.

The primary, initially implanted plate is placed in the appropriatelocation on the patient spine. Plates of this type are usually implantedin patients that must undergo an anterior cervical discectomy andfusion. After the graft has fused with healthy bone growth, somepatients may develop conditions to adjacent vertebra warranting furtherfusion and surgery to repair these conditions. An extension plate may beimplanted so that the previous repair involving the implementation of aprimary or base plate does not have to be removed.

Since surgeons request that the adjacent segment plate is implanted in aminimally invasive manner, the present invention provides a plate systemthat allows the incision to be as small as possible to orient, maneuverand implant the device into the patient. The attached drawingsillustrate the elements of the present invention. Design and utilityfeatures of the present invention are also disclosed. It should be notedthat the angle of the attachment plates can be designed to be differentshapes that correspond to the locking mechanisms.

FIGS. 1-4 illustrate a plate system 10 according to one embodiment ofthe present invention. The plate system 10 consists of base plate 12 andan extension plate 14 used with variable or fixed angle screws. The baseplate 12 is used in the initial procedure and attaches to the anteriorportion of the vertebral body of the cervical spine.

In the event that a secondary procedure is required to addressconditions arising in the adjacent spinal segments to the pre-treatedspinal segments, the extension plate 14 can be used to treat adjacentsegment disease and provide an option to attach onto the cephalad orcaudal end of the base plate without the removal of the base plate. Thepresent invention enables a surgeon to incorporate an extension platerather than removing an original base plate and implanting a new baseplate.

As illustrated in FIG. 1, the cervical plate system 10 includes a baseplate 12, and an extension plate 14. The base plate 10 includes aplurality of screw holes 16 and graft windows 18. The extension plate 14is also provided with screw holes 20 and graft windows 22. Asillustrated in FIGS. 1-4, the base plate 12 and the extension plate 14are configured and dimensioned to be connected to each other via afinger element associated with the extension plate 14. Both the baseplate 12 and the extension plate 14 are provided in a variety of sizesto accommodate surgical needs and anatomic requirements. The base plate12 and the extension plates 14 are configured and dimensioned toaccommodate between 1 and 5 levels of the cervical spine.

Lengths are measured from cephalad to caudal screw hole distance (i.e.hole-to-hole distance). The base plates generally have the followinglengths:

Base Plates 1 Level: 10, 12, 14, 16, 18, 20, 22, 24, 26 mm 1 Level Extra10, 12, 14, 16 mm Lordotic: 2 Level: 24, 26, 28, 30, 32, 34, 36, 38, 40,42, 44, 46 mm 2 Level Extra 26, 28 mm Lordotic: 3 Level: 39, 42, 45, 48,51, 54, 57, 60, 63, 66, 69 mm 4 Level: 60, 63, 66, 69, 72, 75, 78, 81,84, 87, 90, 93 mm 5 Level: 80, 83, 86, 89, 92, 95, 98, 101, 104 mm

Extension Plates 1 Level: 10, 12, 14, 16, 18, 20, 22, 24, 26 mm 1 LevelExtra 10, 12, 14, 16 mm Lordotic: 2 Level: 24, 26, 28, 30, 32, 34, 36,38, 40, 42, 44, 46 mm 2 Level Extra 26, 28 mm Lordotic:

The base plate 12 and the extension plates 14 are connected to thevertebrae through bone screws, which are positioned in the screw holes16, 20. The bone screws may be comprised of any material, such as ametal, alloy, or any combination of the two. The material used toconstruct the plate and the screws allows the plate to maintain itsstructural integrity while allowing for a desired amount of resiliency.Furthermore, the material used is preferably biocompatible and capableof withstanding the conditions of a body over a desired period of time.In some embodiments, this is achieved by manufacturing the plate andscrews using metals such as titanium or stainless steel. Titanium hassufficient ductility to permit a desired amount of curving of the plateto conform to the shape of the vertebrae, yet has the strength tomaintain its structural integrity.

The base plate 12 of the present invention is intended to be positionedwith its longitudinal axis collinear with the spinal midline, and to bemounted on the anterior surface of the vertebral bodies. The length ofthe plate as well as the number of screw holes in the plate will varydepending upon the number of vertebral bodies to be fused.

FIGS. 3 and 4 illustrate the top and bottom view of the plating systemaccording the present invention. FIG. 4 clearly illustrates the screwhole 19 according to the present invention. The screw hole 19 is capableof receiving bone screws, which are directed to be inserted within thevertebra while stabilizing and coupling the extension plate to thevertebrae. In this embodiment of the present invention, the screw hole19 is configured so that the bone screw, when inserted, is directed atan angle in which the bone screw is situated between the bone screwsthat have already been inserted through screw holes 20 and into thevertebrae for implanting the base plate. The base plate 12 and theextension plate 14 each will be discussed in greater detail withreference to FIGS. 5, 6, 7, and 8.

FIGS. 5 and 6 illustrate a top view and a bottom view of the base plate12. In this particular embodiment, the base plate 12 comprises of acenter portion 30 and two distal portions 32. The base plate 12illustrated in FIGS. 5 and 6, is intended to span two vertebral bodies.Although the base plate 12 is adapted to span two vertebral bodies, thebase plate 12 may be designed to span anywhere from two to fourvertebral bodies.

Each distal portion 32 may be attached to a different vertebra usingfasteners, such as screws that pass through screw holes 16. Because thedistal portions 32 are similar, only the operation of one distal portionis described in detail. Each screw hole 16 has a substantially circularshape and the inner portion of the screw hole 16 has substantiallyspherical curvatures. The ends of the distal portions 32 of the baseplate are configured with a spherical curvature. The spherical curvatureof the ends of base plate 12 are provided so as to correspond to theextension plate 14. As illustrated in FIGS. 1-4, the extension plate 14is provided with a spherical curvature that corresponds to the baseplate 12 so that the coupling of the base plate 12 and the extensionplate 14 provide a fit that inhibits lateral motion.

The base plate 12 is also configured with at least one graft window 18that is positioned between adjacent screw holes 16. In this embodiment,the base plate 12 illustrates two graft windows 18 positioned betweenthe two distal ends of the base plate 12. Each of the graft windows 18have edges and at least one of these edges are configured to be able toreceive the hook element or any type of connection element associatedwith the extension plate. The connection element and the extension platewill be discussed in greater detail with reference to FIGS. 7 and 8.

The base plate 12 is shaped so that its bottom surface has a bi-concavecurvature, being concave both in the longitudinal plane and in thetransverse plane. The concave curvature in the longitudinal planeconforms to the proper shape of the anterior aspect of the spine withthe vertebrae aligned in the appropriate lordosis. The base plategenerally has a thickness between 2.0 mm to 4.0 mm, and a thickness of2.3 mm is preferred.

The base plate 12 is also provided with a screw locking mechanism 24that is positioned to be adjacent to each screw hole. The lockingmechanism 24 is provided with a threaded set screw that when actuated,blocks the back out of the bone screw. Specifically, the lockingmechanism inhibits the axial and rotational movement of the bone screwsonce the plate is affixed to the vertebral bodies. FIGS. 1-8 illustratethe locking mechanism 24 in which the set screw is permanently housed inan aperture adjacent to the screw holes. When the set screw is in anunlocked position, the bone screw can be positioned within the screwhole and advanced into the vertebrae. As the set screw is actuated byusing a screw driving instrument, a portion of the set screw inhibitsthe bone screw from backing out of the vertebral body.

The plate system of the present invention may be configured to aid inthe insertion of bone screws. For example, both the base plate and theextension plate may have one or more openings that are capable ofsecurely receiving a drill guide. For example, the screw holes may beconfigured with treads that engage with a threaded tip of a drill guide.In addition, the plate may also have one or more recesses, pivot points,depth stops, or areas of removed material in the top surface of theplate that help align the drill guide opening over the holes of theplate. The drill guide may have a rotating barrel that rotates along anaxis that extends through the recess of the plate.

FIGS. 7 and 8 illustrate more clearly the extension plate according tothe present invention. The extension plate 14 is configured with aproximal end 40 and a distal end 42. The proximal end 40 is configuredto be narrower in width than the distal end 42 of the extension plate14. The proximal end 40 is also provided with a finger portion 44 thatis configured and dimensioned to connect with the base plate 12. Theproximal end 40 of the extension plate 14 is provided with a screw hole19 and a instrument guide hole 46 as well as a graft windows 22. Thescrew hole 19 is configured and dimensioned to receive a bone screw thatis inserted into the vertebrae at an angle that positions the screwbetween the bone screws of the adjacent base plate.

In this particular embodiment, the finger portion 44 is furtherconfigured with a hook element 48 which is used to connect to the baseplate 12. The hook element 48, as illustrated in FIGS. 7, 8A, and 8B, isconfigured to be able to couple with the graft window portion 22 of thebase plate 12. FIG. 8b more clearly illustrates the connection betweenthe base plate 102 and the extension plate 102. The hook element 48 isconnected at the bottom edge 49 of the graft window 18 of the base plate102. It should be noted that the thickness and dimensions of the hookelement 48 and the finger portion 44 of the extension plate may beadjusted and configured to optimize the space available in the anteriorportion of the spine. Although, the present embodiment illustrates ahook element, various other mechanisms such as clips, notches, dovetailsand others may be used to connect one plate to another. Any type ofconnection element connecting the extension plate to the base plate maybe used. Also illustrated in FIG. 8, the extension plate 14 is providedwith a graft window 22 having an edge that is capable of receiving ahook element or any type of connection element from another extensionplate.

FIGS. 9A, 9B, and 9C illustrate an instrument 60 for implanting the baseplate and the extension plate within the spine. The instrument 60 isconfigured with a proximal portion 62 and a distal portion 64. Thedistal portion 64 is configured with an end 66 that is coupled with theinstrument 60 receiving hole 46 in the base plate and/or extensionplate. The implanting instrument 60 also includes a middle portion 68that contains a coupling element to receive a variable drill guide fordirecting a bone screw through the screw hole of the base plate and/orthe extension plate.

FIG. 10 illustrates the present invention positioned on the anteriorportion of spine. The base plate 12 and the extension plate 14 arepositioned over five levels of the spine.

Now turning to FIGS. 11 and 12, another embodiment of the presentinvention is illustrated. In these particular embodiments, the anteriorplating system 100 consists of a base plate 102 and an adjacent segmentplate 104, if needed. It should be noted that the adjacent segment plate104 is only used when the patient's diagnosis dictates it. The baseplate 102 is provided with cavities on both ends so that if additionalsegment plates are required, they can be incorporated either superiorlyor inferiorly depending on where the patient requires treatment. As canbe seen in FIG. 11, the base plate 102 and the adjacent segment plate104 are provided with features that allow for joining The base plate 102and adjacent segment plate 104 are geometrically shaped to provide bonescrew holes 106, blocking set screws 108 and graft windows 114. Theadjacent segment plate 104 is also provided with a sleeve forincorporating additional segment plates, if needed. A hexagonal drivescrew 112 in combination with a fastener 118 is used to lock theadjacent segment plate 104 to the base plate 102. The base plate 102 andthe adjacent segment plate 104 are both provided with end caps 110 whichcover the cavity where a finger portion 118 from an adjacent segmentplate 104 is received.

FIGS. 13-15 illustrate the components of the present system.Specifically, FIGS. 13A-13E illustrate the base plate according to theone embodiment of the present invention. FIGS. 13A-13E illustrate thetop, bottom, and side views of the base plate 102. As can be seen inFIG. 13E, the base plate 102 is provided with a concave geometry toconform with the shape of the anterior spine.

FIGS. 14A-14E illustrate the top, bottom, and side views of an adjacentsegment plate according to one embodiment of the present invention. Theadjacent segment plate 122 is shown have a two screw holes 124 and screwblocking mechanisms 126. The adjacent segment plate is also shown havinga finger portion 128 having a lip 130. The lip 130 is inserted into thecavity of the base plate. FIG. 14A also illustrates a hex screw drive132 for actuating the fastener element 134. The fastener element 134 isactuated or turned when the screw drive 132 is operated with a hex screwdriver to lock the adjacent segment plate to the base plate. FIGS.15A-15E illustrate the different views of the fastening element. As seenin FIG. 15B, the fastener is operated as a cam device to lock theadjacent segment plate with the base plate. The fastener 134 ispositioned within the cavity of the base plate when turned by the hexscrew driver.

Now turning to FIGS. 16 and 17A-17C, the connection of the base plate140 with the adjacent segment plate 142 will be described in greaterdetail. During surgery, the base plate 140 is readied for receiving theadjacent segment plate 142 by removing the end cap (not shown)positioned on either the superior or inferior portion of the base plate140. After the end cap is removed and the cavity 144 is cleaned of anytissue, the finger portion 146 of the adjacent segment plate 142 isinserted into the receiving pocket cavity 144 of the base plate 140. Atthe tip of the finger portion 146, there is provided a curved lip 148which is inserted into an accommodating lip reception area 150 (FIG.19A) located in the cavity of the base plate 140.

The position of the adjacent segment plate can be adjusted since theyprovide space between the curvature of the finger portion and the curvedouter portion of the screw hole. In one embodiment, the adjacent segmentplate is adjustable 4 degrees from the medial axis of the spine. Oncethe desired alignment is made, the hex drive fastener 152 is rotated tothe left until the alignment arrows meet and both plates are rigidlyconnected. The hex drive fastener 152 is a disc shaped device thatutilizes the geometry of the plate to draw the plates together tightly.The adjacent segment plate is then attached to the vertebral bodythrough the use of bone screws inserted in the screw holes 158. Once thebone screws are positioned, the blocking mechanisms 158 are actuated toinhibit the bone screws from backing from the vertebra and plate.

FIGS. 18A-18C illustrate a one, two, and three level base plate andFIGS. 18D and 18E illustrate a one and two level adjacent segment plate.

FIGS. 19 and 20 illustrate yet another embodiment of the extensionplates according the present invention. FIG. 19 illustrates a two levelextension plate 160 having a plurality of screw holes 162 in a baseportion 164 with adjacent screw locking mechanisms 166. The base portion164 is provided with multiple graft windows 168 and an instrumentreceiving hole 170. The extension portion of the extension plate isprovided with a screw hole 174, screw locking mechanism 176, and aninstrument receiving hole 170. The extension portion 170 is configuredto be narrower than the base portion 164 of the extension plate 160. Thescrew hole 170 is capable receiving bone screws which are directed to beinserted into the vertebra. In this embodiment of the present invention,the screw hole 174 is configured to angulate so that the bone screw isdirected at an angle in which the bone screw is situated between thebone screws that have already been inserted into the vertebrae forimplanting a base plate.

FIG. 20 illustrates a one level extension plate 178 having a pluralityof screw holes 180 in a base portion 182 with adjacent screw lockingmechanisms 184. The base portion 182 is provided with a graft windows185 and an instrument receiving hole 186. The extension portion 188 ofthe extension plate is provided with a screw hole 190, a screw lockingmechanism 192, and an instrument receiving hole 194. The extensionportion 188 is configured to be narrower than the base portion 182 ofthe extension plate 178. The screw hole 190 is capable receiving bonescrews which are directed to be inserted within the vertebra whilestabilizing and coupling the extension plate 178 to the vertebrae. Inthis embodiment of the present invention, the screw hole 190 isconfigured to angulate so that the bone screw is directed at an angle inwhich the bone screw is situated between the bone screws that havealready been inserted into the vertebrae for implanting a base plate.

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions, andalterations can be made herein without departing form the spirit andscope of the invention as defined by the appended claims. Moreover, thescope of the present application is not intended to be limited to theparticular embodiments of the process, machine, manufacture, compositionof matter, means, methods, and steps described in the specification. Asone of ordinary skill in the art will readily appreciate from thedisclosure of the present invention, processes, machines, manufacture,compositions of matter, means, methods, or steps, presently existing orlater to be developed that perform substantially the same function orachieve substantially the same result as the corresponding embodimentsdescribed herein may be utilized according to the present invention.Accordingly, the appended claims are intended to include within theirscope such processes, machines, manufacture, compositions of matter,means, methods, or steps.

What is claimed is:
 1. A surgical method comprising: providing anextension plate for attachment to a base plate that extends across oneor more vertebra, wherein the base plate comprises a proximal end, adistal end, a plurality of screw holes for receiving screws therein andone or more graft windows, wherein the extension plate comprises aproximal end, a distal end, a plurality of screw holes for receivingscrews therein, wherein the proximal end of the extension platecomprises a finger portion connectable to the base plate; positioningthe extension plate over the base plate such that the finger portion isreceived through at least one of the one or more graft windows of thebase plate; and inserting screws through the plurality of screw holes ofthe extension plate to secure the extension plate relative to the baseplate.
 2. The surgical method of claim 1, wherein the extension plate isprovided over a cervical portion of a spine.
 3. The surgical method ofclaim 1, wherein the base plate includes at least two graft windows. 4.The surgical method of claim 3, wherein the at least two graft windowsextend through a midline of the base plate, and the plurality of screwholes are offset from the midline of the base plate.
 5. The surgicalmethod of claim 1, wherein the base plate comprises at least six screwholes.
 6. The surgical method of claim 1, wherein the finger portion ofthe extension plate comprises a hook element.
 7. The surgical method ofclaim 6, further comprising positioning the hook element of the fingerportion along a bottom edge of at least one of the one or more graftwindows.
 8. The surgical method of claim 1, wherein the proximal end ofthe extension plate is narrower than the distal end of the extensionplate.
 9. The surgical method of claim 1, wherein after inserting screwsthrough the plurality of screw holes of the extension plate to securethe extension plate relative to the base plate, at least a portion ofthe extension plate remains over and in direct contact with the baseplate.
 10. The surgical method of claim 1, wherein the base platecomprises a plurality of locking mechanisms, each associated with anindividual screw hole, for preventing backout of a screw that isinserted through the screw hole.
 11. A surgical method comprising:providing an extension plate for attachment to a base plate that extendsacross one or more vertebra, wherein the base plate comprises a proximalend, a distal end, a plurality of screw holes for receiving screwstherein and one or more graft windows, wherein the extension platecomprises a proximal end, a distal end, a plurality of screw holes forreceiving screws therein, wherein the proximal end of the extensionplate comprises a hook element connectable to the base plate;positioning the extension plate over the base plate such that the hookelement is in contact with an edge of at least one of the one or moregraft windows of the base plate; and inserting screws through theplurality of screw holes of the extension plate to secure the extensionplate relative to the base plate.
 12. The surgical method of claim 11,wherein the distal end of the extension plate is wider than the proximalend of the extension plate.
 13. The surgical method of claim 11, whereinthe base plate is concave in a longitudinal plane.
 14. The surgicalmethod of claim 11, wherein the base plate is concave in transverseplane to the longitudinal plane such that the base plate has abi-concave curvature.
 15. The surgical method of claim 11, wherein thebase plate has a thickness between 2.0 mm and 4.0 mm.
 16. The surgicalmethod of claim 11, wherein each of the plurality of screw holes of thebase plate includes a locking mechanism for preventing back out of ascrew received therein.
 17. The surgical method of claim 11, wherein thehook element has an upper surface that is in contact with a bottomsurface of the base plate.
 18. The surgical method of claim 11, furthercomprising rotating one or more screw locking mechanisms to prevent thescrews from backing out of the extension plate.
 19. The surgical methodof claim 11, wherein the extension plate comprises at least five screwholes.
 20. The surgical method of claim 11, wherein the one or moregraft windows are positioned between the plurality of screw holes on thebase plate.